The use of simulated physiological structures for training medical students and providing skill training for practicing physicians is widespread. Although cadavers have traditionally been beneficially employed for this purpose, cadavers are not always readily available and are not well suited for all types of training.
Simulated physiological structures should preferably be usable repeatedly and should provide a realistic training experience corresponding to what the trainee would expect if applying a procedure on an actual patient. Students, and even practicing physicians and nurses, often need to be tested to determine their skill level with respect to certain procedures. Since an objective standard is preferable in conducting such tests, a simulated physiological structure should include systems for providing feedback indicating how well the student or physician is performing a simulated task.
The need for such simulators should not be underestimated, because they can provide valuable training that will lead to more effective treatment of patients. For example, medical personnel who administer emergency trauma care can greatly benefit from the training achieved using a simulated physiological structure. Training in administering trauma surgical procedures, which include those procedures that are usually performed on a person who has experienced some form of severe and often life-threatening injury, is particularly beneficial. Such procedures may aid in the diagnosis of a condition, or may provide immediate life-saving care until more complete medical treatment is available. The procedures may include clearing a blocked airway or draining accumulations of fluids from internal organs. While appearing to be simple procedures, if these procedures are performed improperly, the result can worsen the patient's condition, placing the patient at an even greater peril of death. By their nature, trauma procedures are usually performed under emergency conditions in which the person administering the care is under time-related stress. It is therefore useful to provide training methods and apparatus to fully prepare students and physicians in these procedures, so that they can be performed without delay, under stressful conditions.
It should be noted that one reason why the use of a training model (either a cadaver, an animal, or a simulator) is desirable is that while anatomy follows general rules; variations based on sex, age, height, and weight are the norm. A surgical student cannot simply be provided directions such as “make an incision four inches long and two inches deep, starting at the navel.” Normal variations such as the amount of body fat will significantly change the depth of fat tissue that must be incised to reach an internal organ. Surgeons must rely on their knowledge of general anatomy, and visual cues (i.e. the patient has low body fat, the patient has high body fat, the patient is a child, the patient is an adult, the patient is a female, etc.) to determine the correct location on a specific patient for performing a procedure. The use of cadavers, animal models, and anatomically correct simulators enable surgical students to apply their knowledge of anatomy to determine the proper position for executing a procedure.
To provide the desired level of realism, a simulated physiological structure used for training medical personnel should provide tactile sensations during a simulated procedure that faithfully portray the tactile sensations experienced during an actual procedure performed on a patient. Human anatomical models have been proposed using elastomeric compositions for human tissue. However, most elastomeric-based simulators that have previously been created do not include a level of detail that faithfully portrays the finer aspects of human tissue, including the tactile feel of different types of tissue.
Even if a simulated physiological structure having simulated tissue faithfully portrays finer details of an actual physiological structure and provides a realistic tactile sensation during a simulated procedure, prior simulators do not include means for producing objective and measurable results that can be used to evaluate how well a simulated procedure is performed. Clearly, it would be desirable to employ a simulated physiological, structure that is able to provide a realistic tactile sensation during a simulated procedure, and which is also able to provide an objective indication that can be used to evaluate how well a simulated procedure was executed.
One of the key requirements for such a simulator is that physically flexible electrical circuitry be included within the elastomeric material that represents tissue and other flexible organic elements, without changing the tactile characteristics of the elastomeric material. For example, flexible elastomeric conductive materials can be employed to produce flexible circuits that would be usable in a simulator. Sanders et al. (U.S. Pat. No. 5,609,615) discloses a cardiac simulator including an electrically conductive polymer. Thus, medical devices including electrically conductive polymers are known in the art. Indeed, other patents disclose the use of electrically conductive polymers in medical treatment devices (see for example: U.S. patent application Ser. No. 2001/0000187 (Peckham et al.) describing prosthetics; U.S. Pat. No. 6,532,379 (Stratbucker) describing a defibrillator lead; U.S. Pat. No. 6,095,148 (Shastri et al.) describing a neural stimulator; U.S. Pat. No. 4,898,173 (Daglow et al.) describing an implantable electrical connector; PCT application WO 01/32249 (Geddes et al.) describing a tracheotrode; EPO application No. 0601806A2 (Moaddeb et al.) describing a cardiac stimulating electrode; and EPO application No. 0217689 (Compos) describing an ultrasound transducer). Each of the Toth references (U.S. Pat. Nos. 6,540,390; 6,436,035; and 6,270,491) discloses a surgical light that includes a user-actuatable switch that is constructed using conductive elastomers. Kanamori (U.S. Pat. No. 4,273,682) discloses a pressure sensitive conductive elastomer, but not in the context of a simulated physiological structure. Soukup et al. (U.S. Pat. No. 5,205,286) describes an implantable data port that employs an electrically conductive polymer to enable data to be conveyed from an implanted medical device or sensor to an externally disposed data dump. While the data port includes a conductive elastomer, the circuit does not provide evaluation data regarding a simulated procedure and is not part of a simulated physiological structure used for training purposes.
Significantly, none of the above-described medical devices are training devices or models simulating human tissue or physiology, but they do demonstrate some of the advantages of using a conductive polymer. Since elastomeric materials can be employed to produce realistic simulated physiological structures, it would be desirable to provide a simulated physiological structure that includes an evaluation circuit formed from a conductive elastomer that does not alter the tactile sensations of the elastomeric materials with which the conductive elastomer is used. It would be also be desirable to provide a simulated organ that includes a pressure-sensitive conductive elastomer in the periphery of a simulated organ, to enable an evaluation of a trainee's ability to properly manipulate the simulated organ. The prior art does not disclose simulated physiological structures that can provide these important capabilities.